Why YSK: No sense in making the locals mad unless you mean to. In some Middle Eastern countries, a thumbs-up is comparable to the middle finger. A peace sign in the UK is OK if your palm is facing away from you; otherwise, it’s an insult. Pointing with your index finger is offensive in Malaysia. An OK symbol is not OK in Brazil, it’s that smelly hole you normally sit upon.
Reader’s Digest did an entire article on these gestures: https://www.rd.com/article/common-hand-gestures-rude-in-other-countries/
The head wobble doesn’t have one simple meaning.
https://www.youtube.com/watch?v=9gbrB8KwES4
I worked for many years with someone from south India and he would do the head wobble so over the years he tried to explain it. I still don’t fully understand it. Haha
I’ve been watching Bollywood movies since I was a kid and I still can’t replicate the sideway head wobble. It’s surprisingly difficult!